A control system for a vehicle has been known that identifies road signs and the like that represent the speed limit values on a road on which the vehicle is traveling, by using image information captured by an imaging device installed in the vehicle, recognizes the speed limit value, and limits the speed of the vehicle (see, for example, Japanese Laid-open Patent Publication No. 2005-128790).
By using the control system for a vehicle, road signs and the like located at positions on the road can be captured while the vehicle is traveling, and based on the speed limit values at the respective positions on the road, the vehicle speed can be limited.
However, if the condition of capturing an image is inadequate, such a control system for a vehicle may fail in recognizing a speed limit value that should be recognized from the captured image information. Especially, if inadequate capturing conditions are repeated, a state continues in that the speed limit value cannot be recognized even if the vehicle travels for a certain distance. In this case, the control system for a vehicle executes limiting the speed of the vehicle, by using a speed limit value that has been recognized before the state where the inadequate capturing conditions are repeated, and there is a likelihood that the speed limit value currently referred to by the system may be different from the actual speed limit value on the road on which the vehicle is traveling now.
In contrast to this, another technology has been known that estimates the speed limit value on a road, based on information other than road signs and the like (e.g., information provided by a navigation device). By using this technology, it is possible to estimate the speed limit value on a road even if the speed limit value cannot be recognized based on captured image information, and hence, it is possible to execute limiting the speed of the vehicle, by switching to the estimated speed limit value.
However, a speed limit value estimated based on information provided by a navigation device may not be always equivalent to the speed limit value on the road while traveling. This is because if the information stored in the navigation device is not the latest information, a speed limit value may be estimated that is different from the actual speed limit value on the road.
Therefore, if a system is configured to execute switching to the estimated speed limit value upon a failure in recognizing the speed limit value based on the captured image information, there is a likelihood that the speed limit value currently referred to by the system may be different from the actual speed limit value on the road on which the vehicle is traveling now.
Thereupon, it is an object of the disclosure to provide a control system for a vehicle to execute limiting the speed of the vehicle, that can avoid limiting the speed limit by a speed limit value that is different from the actual speed limit value on the road.